Propeller auxiliary power control



Jan. 13, 1959 c. M. JEDRZIEWSKI PROPELLER AUXILIARY POWER CONTROL AUX.M070 "m l i 4 m m M 3 M u 2 p d INVENTOR CHESTER l4. \JElNiZ/E SK/ gym7% 6 m U 6 4 a 7 k Z 3W 4 M Z r W w/ W u mw 5 E 0 7% u o 6 a mfw m 0 476F .0 2 2 005/ w u 9 M m $0 a U Mn cam E! ZZ d,

United States Patent PROPELLER AUXILIARY POWER CONTROL Chester M.Jedrziewski, Roekville, Conn., assignor to United Aircraft Corporation,East Hartford, Conn., a corporation of Delaware Application September'2, 1953, Serial No. 378,096

19 Claims. Cl. 170160.2)

This invention relates to improved propeller control mechanism andparticularly to an improved power supply system for power actuated pitchcontrol mechanism.

An objectof this invention is a light and eflicient fluid supply systemfor a hydraulically actuated propeller.

A further object is mechanism by which a pump of small capacity isutilized for normal pitch changesand an auxiliary pump is automaticallyconnectedin parallel with said small pump for larger or more rapid pitchchanges.

A still further object is mechanism under the control of the governorfor increasing the volume of fluid supply when the governor reaches apredetermined off speed position.

A further object is the provision, in a governor having contactsclosable by movement of the governor to supply governing power, of meansfor supplying governor power while the contacts are open.

A still further object is an improved propeller governing system. i

Other objects and advantages will be. apparent from the specificationand claims, and from the accompany ing drawings which illustrate what isnow considered to be the preferred embodiment of the invention. 1

Fig. l is a somewhat schematic end view of the propeller controlmechanism including a schematic wiring diagram.

Fig. 2 is a schematic side view showing the hydraulic control mechanismand the pitch changing mechanism.

Fig. 3 is a partial wiring diagramiilustrating how the wiring diagram ofFig. 1 may be changed for operation of the governor switch in bothdirections.

In the drawings which illustrate a mechanical construction which is nowconsidered the preferred form of the invention, a propeller of the typeshown in application 84,305, filed March 30, 1949, by John E. Andersonis utilized. Reference may be made to that application for a morecomplete description of the propeller and its control. In general thepropeller comprises a control unit indicated generally at rotatablysupported on bearings on the propeller unit indicated generally at 12.The control unit it includes a bearing sleeve 14 which is telescopedwith and supported on an axial projection 16 on the hub 18 of thepropeller 12 The sleeve 14 is secured in position on the hub and heldagainst axial or rotational movement thereon, as more fully described inthe above-mentioned application.

The propeller may be of any type utilizing hydraulic fluid for pitchchanging and preferably having the propeller pitch changing motorcarried by and rotating with the propeller. In the preferred form, thepitch changing motor comprises a piston mounted in a cylinder 34 and bymeans of cam slots 36 and cam rollers, not shown, turns a connectinggear 35 geared to the propeller blades 40 to thereby change thepropeller blade pitch. Oil may be selectively directed to either side ofthe pitch changing mechanism by means of conduits 42 and 44. Thepropeller is secured to a propeller or engine shaft 46 supported'in theusual manner by hearings in the engine 190 or engine nose. For furtherdetails 'of these propeller constructions, reference may be made toPatent No. 2,477,868of George W. Forman, filed April 17, 1946, andissued August 2, 1949. Reference may also be made to Patent No.2,371,873 of Erle Martin, issued March 20', l945, for a furtherdisclosure of a suitable type of propeller for use with the control ofthis application. As this type of propeller is now well known, furtherdetailed description thereof is believed to be unnecessary.

Hydraulic fluid is led from the control mechanism to the propellerthrough the conduits 42 and 44 in the propeller hub. Conduit 42 leadinginto the hub outside of propellershaft 46 and through suitableconnections such as shown in Patent No. 2,477,868, is led to the forwardside' of piston 32. Fluid may also be led through conduit 44 in the hubto the interior of the propeller hub and the space to the rear orinboard side of piston 32 Suitable means such as a gasket 48 preventsflow of oil inboard along the propeller shaft, the propellersurrounding' the outboard end of the propeller shaft closes the outboardend against the loss of oil in the outboard direction. Oil from thecontrol mechanism is directed into a groove 54 on the inside of sleeve14, which when assembled on hub projection 16, is in hydrauliccommunication with conduit 42. Oil may also be led from the control unitinto groove 64 formed in the interior of bearing sleeve 14. Groove 60,when assembled on the hub projection 16, is in hydraulic communicationwith the conduit 44."

The control unit 10 comprises a main casting 74 which supports all ofthe various control elements, including the governor valve indicatedgenerally at 76, the scavenge pump, indicated generally at 78, the mainpump and its connections indicated generally at 30, the auxiliary pumpand motor indicated generally at 82, the various valves and theircontrols, to which reference will be made hereinafter, and the oilreservoir, indicated generally at 84. The various control elements arepreferably separate units bolted or otherwise removably secured to themain casting' A hearing sleeve 86 is secured in main casting '74 andserves to rotatably support the entire control system onthe bearingsleeve 14 which is secured as previously described on the hub projection16. Bearing sleeve 86 is provided with a bearing metal such as babbitton its inner diameter and inboard face which provides a bearing surfacecooperating with the outer surface of bearing sleeve 14 to provide asuitable running joint between the stationary control unit and therotating propeller unit.

' Four grooves 88, 90, 92 and 94 are provided in the outer surface ofbearing sleeve 86 and, like the grooves in the interior of sleeve 14,are prevented from leaking by means of suitable 0 ring gaskets. Suitablepassages lead from groove 94 through sleeve 86 and other pas sages leadfrom groove 88 through sleeve 86. Suitable passages'lead from grooves 88and 94 to the governor valve which being thus connected with thepropeller pitch changing mechanism controls the flow of oil to and fromthe pitch changing mechanism. The main and auxiliary pumps are connectedin parallel and their output is led to groove 92. Various passages inthe main casting connect with groove 92 to deliver the output of themain and auxiliary pumps to the low pressure relief valve, indicatedgenerallyat 96, high pressure relief valve, indicated generally at 98,and to the governor valve 100. A passage 102 connects the auxiliary pump104, driven by auxiliary motor 106 withpassage 92. As will be explainedlater, this auxiliary pump and motor are used to provide pressure fluidto assist the main pump, and also to provide pressure fluid when thepropeller is not r'otati'ng and the main pump is consequently idle.

. v3 r Suitable check valves'354, 356 are placed in the output line ofthe auxiliary'and main pumps to assist in preventing bleeding of oilthrough these pumps when they are idle or otherwise inoperative.

A main sump or reservoir is formed at one side of the main casting 74 ofthe'control unit which is the lower side when the control unit is in itsnormal upright position, by means of a curved, tro'u'gh like cover 108secured to the lower portion of main casting 74. The main pump 80 isenclosed by the cover 108 and comprises a gear pump 116 driven throughgear 118 by a gear 120 formed on an upstanding flange 122 on the inboardside of sleeve 14 secured to rotate with the propeller. Pump 116 has aninlet 124 located near the bottom of the reservoir. This inlet, however,is spaced from the bottom of the reservoir a greater distance than inlet126 leading to auxiliary pump 104 so that in the event of failure of thepropeller to change pitch due to lack of oil it may still be possible tofeather the propeller by means of the auxiliary motor which can stillpump oil if the lack of oil is caused by the level falling just belowthe inlet to the main pump.

As stated above, oil from main pump 116 is led to passage 92 and thenceto the governor valve 100 from where it is directed in the usual mannerby the governor to the proper side of the pitch changing motor tomaintain constant propeller speed by varying the propeller pitch. Thegovernor is driven from gear 120 by gear 136 and a pair of bevel gearsas shown in Fig. 2. The governor comprises the .usual' flyweights 140opposedby a speeder spring whose tension may be adjusted in a well knownmanner from the pilots cockpit. Pressure 'oil is also lead throughpassage 144 to solenoid actuated feathering valve 146 and solenoidactuated reversing valve 148 which are normally closed. Actuation of thefeathering valve will direct pressure fluid through conduit 150 to theunderside piston 152 on the lower side of governor valve 100 to therebyraise the governor valve 100 and connect pressure fluid with groove 88and the pitch increasing side of the piston 32 of the pitch changmgmotor.

Actuation of the reversing valve will direct pressure fluid from thepassage 144 to passage 154 leading to'a piston 155 on the top of thegovernor valve 100 thereby forcing the pilot valve down to directpressure fluid from groove 92 into groove 94 and thence to the pitchreducing side of the piston 32 in the pitch changing motor.

Pressure oil is also led from the passage 92 to the front face ofplunger 156 of relief valve 96 which is urged into closed position byspring 158. The relief setting of relief valve 96 is normally determinedby the capacity of spring 158 but may be increased by leading oil underpressure to the backside of plunger 156. This is accomplished by ashuttle valve 160, one side of which is connected with the reversingvalve 148 and piston 155 on the governor valve 100 and the other side ofwhich is connected with the groove 88 leading to the pitch increasingside of the pitch changing motor. Hence, whenever the reversing valve isopened or whenever pressure fluid is being led to the pitch increasingside of the pitch changing motor, the capacity of the relief valve 96 isincreased to thereby increase the pressure output of the main pump.Shuttle valve 160 moves under the predominant pressure acting thereon toconnect that predominant pressure with the rear of the plunger 156.

Groove .92 is also connected with a high pressure relief valve 98 whichserves to limit the ultimate pressure attainable by the main pump. Bothrelief valve 96 and 98 discharge directly into the main sump orreservoir, relief valve 96discharging through conduit 161.

Gears 162 of scavenge pump 78 are driven by gear 120 and serve to removeoilthat may collect in the drainage area 166 and force it into thereservoir, 84 to keep thedrainage area free from an accumulation of oil.4 and maintain reservoir 84 under a pressure determined by thereservoir relief valve indicated generally at 170: Pump 78 may pump bothoil and air to maintain the reservoir pressure. y I

The main casting 74 has projections 186 extending from one side thereofand forming a slot between than. A lug fixed on theefzgihe nose extendsto a position be tween said pro ections and acts to prevent rotation ofi the control unit with the propeller while permitting it to moveaxially and radially with the propeller.

In normal constant speed operation the governor 76 operating valve 100controls the flow of oil through pas sages 42, 88, 44 and 94 to maintainconstant propeller speed by varying the propeller" pitch. Shuttle valve160 is maintainedin the position shown in Figure 1 to ap= ply pressureback of relief valve plunger 156 whenever pressure-oil is introduced tothe pitch increasing side of the pitch changing motor, scavenging pump162 serving to keep drainage area 1'66 free from the accumulation of oiland to maintain a predetermined pressure in reservoir 84.

It has been customary to utilize continuously rotating pumps such asmain pump to supply all the hydraulic fluid for changing pitch duringconstant speed opera; tions. During the major portion of the constantspeed.

1 operation, only a small quantity of hydraulic fluid is r= qulred butduring extreme operations such as rapid throt tle changes, the entirecapacity of the main pump is utilized. Hence the main pump had to belarge enough to supply fluid at a rate suflicient to provide the rapidpitch change necessary for these extreme operations. Hence, during themajor portion of the time the main pump was pumping an excess of fluidwhich caused undue heating and a waste of power.

In the present invention applicant has provided means by which thenormally stationary auxiliary pump 104 may be utilized to assist themain pump during extreme operations thus permitting a material reductionin the size of the main pump with a consequent reduction of powerrequired and a reduction in the resultant heat of the oil.

A normally open switch 351 having contacts mounted on spring arms ismounted in the governor housing in a position to be actuated by the rod352 which in turn is actuated by the pilot valve Whenever the governorexceeds a preselected overspeed condition. The rod 352 may be suspendedin the switch housing and normally spaced at its lower end from thegovernor valve 100 or it may be constructed as shown as an integralextension of the valve 100. The upward movement of the valve 100 thusserves to close the switch 351. Closing of the switch 351 will energizehold-in coil 311 and energize the auxiliary motor to start the auxiliarypump 104 and assist the main pump 116, thus supplying the additionalfluid necessary to give a pitch change rapid enough to avoid anyexcessive overspeeding.

In general, it is not necessary to have as rapid a pitch reduction as apitch increase as the underspeeding which will call for a pitchreduction does not produce dangerous conditions. However, if desired,another switch could be provided as shown in Fig. 3 which would beactuated by the governor valve when it approaches its extreme underspeedposition which switch could be placed in parallel with switch 351 toenergize the auxiliary motor 106 and operate the pump 104 to assist themain pump 116 in pitch reducing movements.

The above mechanism connected with the auxiliary motor 106 does notinterfere with the utilization of this auxiliary motor for feathering,unfeathering and, if desired, reversing and unreversing operations aswill he explained below. v When it is desired to feather the propeller,feather but ton 192 in the control compartment of the airplane is I"1192'depressed. This Will -also opeir feathering valvei146, .energizetfeatheringr'solenoid 204*andholding coil 311 cclosingswitch 313 forauxiliarypumpmotor 1'06,.and operate auxiliary pump .104to supply fluidin addition :to that being supplied by the (main pump and to, if neces-:tsary, continue to supply fluid after the main pump has ceasedoperation due to stopping of the propeller. Hold- ,ing coil 202 isinseries with a cut-out switch 206 which a is actuated by thepressurefluid changing the propeller ;pitch. Opening of featheringvalve'146 allows pressure ufluid from grooves 92 and passage .144 toenter conduit 150 and act on the underside of piston 152. to liftgovernor valve100 which will direct fluidfrom the groove 92 to 'groove88and the pitch increasing side of the pitch changingmotor. Lifting of thegovernor valve 100 by the piston l52 will actuate rod-352 to closeswitch 351 and provide a second path for electricity for'hold-in coil311 for auxiliary pump switch 313. Pressure oil in groove i88will moveshuttle valve 160to the position shown to put pressure oil back-ofplunger 156 of relief valve% andwill move shuttle valve 208 from theposition shown to .thelower end of its cylinder to thereby connect thepressure cut-out switch with the pitch increasing side of the pitchchanging motor. When the pitch changing motor has reached its limit ofmovement determined by stops, not shown, the'pressure. at the pitchincreasing side .of the pitch changing. motor will increase creating apressure surge which will open thepressurecut-out switch releasing theholding coil.202 and permitting springs 300 to-return the featherbutton192 to its off position as.-

shownin Figure 1. Return of the feather button 192 to its off position.will break thecircuit through contact .200 to hold-in coil 311 and willbreak the circuit through contact 193 to the feathering solenoid 204thus permitting the governor to return under the influence of thespeeder spring to an unders peed condition thus opening switch 351 tode-energizehold-in coil 311 thus stopping the auxiliary motor.

To unfeather the propeller from its non-rotating featheredpositionpbutton 192 is pulled to the left as viewed inFigure 1, closingcontacts 302, 304, 306and 308 to thereby energize holding coil 310closing switches 318 and 318a, energizing holding coil 311 andconsequently energizing auxiliary pump motor 106 and reversing solenoid312 thus opening reversing valve 1443. Operation of auxiliarypump motor106 will supply auxiliary fluid in the same manner as described forfeathering, except that it must supply all the fluid at the beginning ofthe operation as the main pump 116 then does not operate and it willassist the main pump after the propeller starts to rotate. Opening ofreversing valve 148 will allow pressure fiuid from groove92 and passage144 to enter passage '154 and act on theupper surface of piston 155 tothereby force the governor valve 101? down and admit pressure fluid fromgroove 92 to 94 and hence to the pitch decreasing side of the pitchchanging motor. Pressure'fluid in passage 154 will move shuttle valve160 to apply pressure fluid back of plunger 136 of relief valve 96 tothereby increase the available pressure. Pressure in groove 94 will moveshuttle valve 208 to the position shown in Fig. 1 thereby connectingthepitch decreasing sideof the pitch changing motor with the pressurecutout. switch 206. The pressure cut-out switch, however, is notutilized to stop the unfeathering operation as this is accomplished byelectrical contacts on the propeller blade shank. When the propellerblade has reached a predetermined position in itspitch reducing movementthe current in holding coil 310 is broken by an insulating segment 314thus releasing holding coil 310 allowing spring 316 to return switch 318to an off or neutral position thus breaking the current to reversingsolenoid 312 and auxiliary motor 106. The plunger which cooperates withholdingcoil 2 is so far out of the holding coil when button 192 isinunfeather position that holding coil 202 has no affect. Button 192 isheld out manually for unfeathering rand may be? released' at anytimeaafter I. the

trol. As in the feathering operation the switch is returned to itsneutral position by springs 300 after his released. Reference may be hadto application Serial No. 32,244 of Martin and McCarthy, filed June 10,1948 for a more complete description of the construction. and operation.of'the insulatingand conducting segments on the'blade 18. It will besufiicient to state here that by means of a brush, insulated from, andheld in fixed position on the propeller hub an electric circuit maybecompleted by being con ducted to ground through conducting segments328 and 330 and the propeller blade and hub. The brush and segments arearranged :so that the brush will be approximately at the positionindicated byF when the propeller is feathered at the position indicatedby L. P. when the propeller is at its low pitch stops and at R when thepropeller is in its reversed pitchposition. It will thus .be apparentthat even if switch .knob 192 is held in the un feather positionwhenconducting segment 330 contacts the brush, the circuit will again bebroken by insulating segment 332 before the propeller reaches its lowpitch stop. This will prevent the propeller from going into reversepitch while unfeathering because the pressure level maintained by reliefvalve '96 alone, when not backed up. by pressure from reversing valve148, is notsufiicient to overcome the low pitch stops.

In order to reverse the propellerpitch, switch320 is first closed andthen reverse-unreverse switch 322 is moved into the reverse positionwhich is the lower position as viewed in Figure 1. Closing of theseswitches will energize reversing solenoid 312 and holding coils 324 and326. Energizing holding coil 324 will close switchs 334 and 336. Closingswitch 334 will be effect short circuit switch 322 so as to maintainholding coils 324 and 326 energized independent of the position ofswitch '322.

Energizing holding coil 326 will close switch 338 which will in effectshort circuit switch 320 so as to maintain holding coils 324, 326energized independent of the position of switch 320. Energizing holdingcoil 326 will also close switch 354 to start the auxiliary pump inoperation. The closing of switch 336 has no immediate 'elfect, butprepares the circuit for unreversing which will'be described later.After passing through switches 320, 322 and holding coils 324, 326 thecurrent passes through switch340 to ground. Switch 340 is normally heldclosed by spring 342. Energizing the reversing solenoid 312 will producethe same hydraulic action as in unfeathering. As in unfeathering,governor valve is forced down so as to connect groove 92 with groove 94and direct fluid to the pitch reducing side of the pitch changing motor.It is to be understood that as is usual in this double'acting type ofcontrol, each time pressure fluid is conducted to one side of the pitchchanging motor, the opposite side of the motor is connected to drain orthe reservoir to permit fluid to flow from one sideof the motor as it isintroduced to the other side. Switches 320 and 322 remain in the closedposition just described as long as it is desired to have the propellerremain in the reversed pitch position and the propeller is maintained inthat positionby the fluid from the main pump and the auxiliary pumpbeing continuously directed to the pitch reducing side of the pitchchanging motor, thereby forcing the propeller against the reverse pitchor pitch limiting stops not shown. If the reversing operation is to becontinued for any appreciable length of time,it may be desirable todisconnect the auxiliary pump and allow the propeller to be held inreverse pitch by the main pump alone. This can be accomplished byinserting a switch 356 in the line between the switch 354 and theauxiliary motor 106'which switch' may i 338, it has no immediate effect.I the unreverse position will also close a circuit to prepare when itreaches a selected underspeed position.

be manually operated or if desired may be automatically operated by amechanism such as a second blade switch reversed to its unreversedposition, the position shown in Figure 1, which will de-energizesolenoid 312 and close valve 148. In the unreversed position of switch322 the current will be conducted through switch 336 which is stillmaintained closed by holding coil 324 and will energize feathering, orincrease pitch, solenoid 204. Switch 320 is then opened, but as it shortcircuited by switch Placing switch 322 in holding coil 344 for actionwhen the circuit is completed through contact 330. Energizing increasepitch solenoid 204 will cause actuation of the governor valve 100 in thesame manner as was described in the feathering operation closing switch351 to energize the auxiliary pump and motor.

nect groove 92 with groove 80 and apply pressure fluid The governorvalve 100is moved to conto the pitch increasing side of the pitchchanging motor and thus move the blades 18 from reverse pitch throughzero pitch to increased pitch position. After the blade pitch has beenincreased to a pitch somewhat above the pitch defined by the low pitchstops, brush 346 will make contact with conducting segment 330, whichwill energize holding coil 344 to thereby open switch 340. Openingswitch 340 will break the ground connection of holding coils 324 and 326thus de-energizing them. Springs 348 and 350 will now open switches 334and 338 and deenergize increase pitch solenoid 204, closing valve 146and thus opening switch 351 and returning the governor valve 100 togovernor control.

As has been indicated above, the switch actuated by the rod 352 may bearranged so as to be actuated both when the governor reaches a selectedoverspeed position and Fig. 3 illustrates a wiring diagram showing howsuch a switch may be fitted into the above-described structure. The rod352 is attached to the pilot valve 100 for actuation in both directionsin accordance with the position of the pilot valve. As in the singleswitch of Fig. 1, there may be lost motion provided between the governorvalve 100 and the rod 352, or the lost motion may be between the rod andthe switch or even in the switch itself. A lost motion equivalent to 50R. P. M. above and 50 R. P. M. below the onspeed position has been foundto be satisfactory. Shoulders 360 and 362 on the rod 352 are effectiveto acuate the switches upon movement of the rod. Upward movement of therod 352 will cause shoulder 360 to close switch 351 and operate theauxiliary motor 106 as described above.

Shoulder 362 will be moved downward on underspeed and when the governorreaches a selected underspeed condition will close the switch 364 toenergize line 366. A switch 368 connects line 366 with holding coil 311to close switch 313 and actuate the auxiliary motor 106. Switch 368 isclosed by a solenoid holding coil 370 which is controlled by a bladeswitch 372 mounted on one of the propeller blades 40. Blade switch 372has a conducting portion 374 which will keep holding coil 370 energizedand switch 368 closed except near the reverse and feathered positionswhere insulating segments 376 and 380 will fbreak the circuit throughhold-in coil 370 allowing switch 368 to open. Hence, during the normaloperating range,

whenever the propeller reaches a preselected underspeed condition,switch 364 will close and switch 368 will operate the auxiliary motor106. Line 366 is also connected through switch 318a to the hold-in coil311.so

that, when the propeller reaches a feathered position and .stopsrotating, thus causing the the governor to stop rotating, and assume anunderspeed position closing switch v364, although switch 364 will beclosed, it will not operate the auxiliary motor 106 because both switch318a and 368 will be open.

When it is desired to unfeather, button 192 is pulled giving twoparallel connections to coil 311 or the con-.

nection of line 366 with switch 318a may replace the connection betweencontact 308 and switch 318a. The connection between contact 308 and coil310 will of course remain as shown in Fig. 1. In feathering thepropeller the connections between contact 200 and the holding coil 311may be allowed to remain as shown in Fig. 1 or may be removed relyingentirely upon the closing of switch 351 by the movement of the governorincident to operation of the feathering solenoid if desired. It will ofcourse be apparent that operation of the feathering solenoid 204 will,through the resulting movement of pilot valve 100, close switch 351.Operation of the reversing solenoid 312 will, through the resultingaction of the governor valve 100, close switch 364, which switches- 351and 364 can be-utilized for the feathering and reversing actions.

In reversing, actuation of reversing solenoid 312 by placing switch 322in reverse position will close switch 364 and, switch 368 being closed,will actuate the auxiliary motor to assist in reversing. Just before thereverse pitch position is reached, insulating segment 376 will comeunder brush 346 to de-energize coil 370 and allow its spring to openswitch 368 to stop the auxiliary motor 106. The propeller may then beheld in reverse pitch position through the action of the reversingsolenoid 312 by main pump 116.

In unreversing, the feathering solenoid 204 actuated by moving switch322 to unreverse position will act to move the governor to close switch351 and energize coil 311 energizing the auxiliary motor. Thede-energization of the feathering solenoid 204 by the opening of switch336 when coil 344 is energized through contact 330 to open switch 340and break the ground to coil 324, will of course release the governor toopen switch 351 when the propeller speed returns to within 50 R. P. M.of the governor speed setting and the propeller will be returned togovernor control. It will be apparent that the governor actuatedswitches 351 and 364 can be utilized not only for boosting oil flowduring governor control but may also be used in the operations outsideof the governor range for feathering, unfeathering, reversing andunreversing.

If desired, contact strip 374 may be shortened so as to extend fromadjacent the reverse position to only slightly beyond the low pitchposition in the governor range so as to limit the use of the auxiliarymotor to pitch increasing movements during governoroperations. Theswitch 368 being open in the governing and feathering ranges and beingclosed only in the reverse range, and switch 318a being closed only inthe unfeathering operation, the switch 364 will not be effective toenergize the auxiliary motor for pitch reduction in the governing range.Use of switch 364 in operating the auxiliary motor 106 for pitchreduction would therefore be limited to reversing and to unfeathering.

The propeller has been described in connection with a pressure cut-outswitch 206 but if desired a suitable timing mechanism may be substitutedfor the cut-out switch which mechanism instead of operating on apressure surge, will operate to disconnect the auxiliary motor after apredetermined elapsed time.

The timer may be used to measure the elapsed time from the time energyis supplied to the auxiliary motor for feathering and may also be usedto measure the elapsed time from the supplying of energy to theauxiliary motor for reversing, being substituted for the cut-out switchin the first instance and for-the manually actuated switch 356 in thesecond instance.

It is to be understood that the invention is not limited to the specificembodiment herein illustrated and described, but may be used in otherways without departure from its spirit as defined by the followingclaims.

I claim:

1. In combination with a hydraulic governor having a valve controllingthe flow of fluid from a source of fluid pressure to a device to becontrolled, an auxiliary source of fluid pressure, a conduit connectingsaid auxiliary source with said governor valve, a check valve in saidconduit preventing flow fromsaid governor valve toward said auxiliarysource, said conduit being continuously open for flow from saidauxiliary source to said governor valve, means actuated by said governorvalve, when, in its governing operation, it reaches a predeterminedolfspeed position, for supplying additional fluid from said auxiliarysource to said governor valve in parallel with said first mentionedsource.

2;. A. device as claimed in claim 1 including means .for

de-energizing said auxiliary source while the governor is flow of fluidfrom said pump to said outlet, a normally inactive fluid pump connectedin parallel with said continuously operating pump, means actuated bysaid governor, when in its governing operation it reaches apredetermined oif speed position, including means for actuating saidinactive pump, for supplying fluid to said outlet.

4. A control for an adjustable pitch propeller com prising, a fluid pumpactuated by rotation of said propeller, a speed responsive governorcontrolling the flow of fluid from said pump to said propeller tocontrol the pitch thereof, a source of fluid pressure connected inparallel with said pump, an electric switch, means connected with saidgovernor for actuating said switch when the governor in its governingoperation reaches a predetermined off speed position, and meansresponsive to operation of said switch for energizing said source tosupply fluid from said source to said propeller.

\ 5. A device as claimed in claim 4 in which the means responsive tooperation of said switchincludes an electric motor and a pump actuatedthereby.

6. A control for a hydraulically actuated controllable pitch propellerhaving a fluid reservoir and a pump connected with said reservoir fordrawing fluid therefrom and continuously operated by rotation of saidpropeller for continuously supplying hydraulic actuating fluid underpressure during operation of said propeller, a governor for controllingthe application of said fluid to said propeller for controlling thepitch thereof, a second normally inactive pump connected with saidreservoir for drawing fluid therefrom, and means connected with saidsecond pump and actuated by said governor when it reaches a selected offspeed position in its governing operation to actuate said second pumpand supply fluid in parallel with said continuously operating pump.

7. In combination with a feathering type controllable pitch propellerhaving means for supplying fluid from a first source of fluid pressurefor feathering and unfeathering said propeller independent of propellerrotation, a governor for said propeller, a second source of fluid underpressure, means for supplying fluid from said second second sourcethrough said governor to said propeller during normal governed speedoperation, and means responsive to a selected ofl? speed condition ofsaid propeller for automatically supplying additional fluid underpressure during governed operation from said feathering and unfeatheringsupply.

8. A device as claimed in claim 7 in which said first source of fluidpressure comprises an electrically driven pump and the means responsive:to a selected ofispd condition includes a switch actuatedby saidgovernor.

9. A device asclaimed in claim 8 in which saidsecond source of fluidunder pressure includes a pump-operated continuously by rotation of saidpropeller and the pro- -peller includesa common sump for both pumps.

10. A device as claimed in claim 8 including a manually actuated switchfor controlling said source of fluid pressure for featheringandunfea'thering connected in parallel with said governor actuatedswitch.

11. A hydraulic governor having a reciprocating valve for controllingfluid flow, switch means actuatable by said valve adjacent the limit ofits reciprocation, a normally de-energized source of fluid pressureconnected with said governor and controlled by said switch, said valvebeing movable incident to the governing action of said governor toactuate said switch and energize said source and manually controlledmeans for moving said valve to actuate said switch and energize saidsource.

12. In combination with a controllable pitch propeller, a :first sourceof fluid pressure energized by rotation of said propeller, a governorvalve controlling the application of said fluid to said propeller, asecond source of .fiuid presusre independent of rotation of saidpropeller, connected in parallel with said first source, means actuatedby said governor valve when it reaches a predetermined oifspeed positionfor supplying .fluid from said second source to assist said first sourcein governing said propeller.

13. A governor, driving means for said governor, a main pumpcontinuously driven by said governor driving means, means continuouslydirecting the output of said pump to said governor, a second pump,driving means for said second pump independent of said main pump drivingmeans, means including a check valve connecting the outlets of saidpumps, said check valve preventing flow from said main pump to saidsecond pump and opened by an excess of pressure from said second pumpover the pressure of said main pump and connecting said second pump withsaid governor in parallel with said first pump and means controlled bysaid governor controlling said second pump driving means.

14. A device as claimed in claim 13 wherein said governor controlledmeans includes switch means connected with said governor and actuatedthereby for controlling the operation of said second pump driving means.

15. In combination, an engine driven hydraulically actuated controllablepitch propeller, a main pump continuously actuated by rotation of saidpropeller, a governor valve having an onspeed position and oifspeedpositions, means connecting said pump with said valve and meansconnecting said valve with said propeller, said governor valvecontrolling the flow of fluid between said pump and said propeller tovary the propeller pitch and control the engine speed, a second normallyinoperative pump, electric motor means for operating said second pump, aswitch connected with said electric motor, means connected with saidgovernor for actuating said switch to energize said motor when thegovernor, while governing, reaches a predetermined ofi'speed condition,means connecting said second pump with said valve in parallel with saidmain pump.

16. Governor control means for a controllable pitch propeller comprisinga governor valve for directing fluid under pressure to said propeller, anormally de-energized electrically driven pump for supplying fluid underpressure to said valve, governor actuated switches for energizing saidpump, means connected with said governor for closing one of saidswitches and energizing said pump when the governor reaches apredetermined overspeed condition, and closing another of said switchesand 'energizing said pump when the governor reaches a predeterminedunderspeed condition, and additional means for supplying fluid to saidgovernor for governing said propeller between said oifspeed conditions.

17. In combination with a governor having an onspeed position and havinggovernor-controlled electrically-actuated means for supplying speedcorrecting forces on opposite sides of said onspeed position, saidgovernor having a dead band at and adjacent the onspeed position of saidgovernor in which said electrically actuated means are inoperative, andmeans controlled by said governor for supplying speed correcting forcesin said dead band independent of said electrically actuated means.

18. In combination with a controllable pitch propeller, a first sourceof fluid pressure energized by rotation of said propeller, a governorcontrolling the application 'of said fluid to said propeller, a secondsource of fluid pressure independent of rotation of said propeller,connected in parallel with said first source, means actuated -by saidgovernor when it reaches a predetermined offerning range into a specialpurpose range and actuating -said means actuatable by said governor tosupply fluid 'to move said propeller in said special purpose range.

1.9. Control means for a controllable pitch propeller having a governedrange of pitch change and a special purpose range outside of saidgoverned range, compris ing a source of energy, a speed responsivegovernor controlling the application of said energy to said propellerfor controlling the pitch changing movements of said propeller in thegoverned range, a second source of energy for actuating said propellerin said special purpose range when the propeller is not rotating, meansactuated by said governor in its governing action when it reaches apredetermined ofispeed position for controlling the sup ply of energyfrom said second source to said propeller in parallel with said firstsource, means for disabling said governor and moving it to one extremelimit of its travel to actuate said governor actuated means and supplyen ergy from said second source for moving said propeller in saidspecial purpose range.

References Cited in the file of this patent UNITED STATES PATENTS2,229,058 Dicks Ian. 21, 1941 2,402,065 Martin June 11, 1946 2,413,439Drake Dec. 31, 1946 2,545,684 Carson Mar. 20, 1951 2,611,440 Haworth etal Sept. 23, 1952 2,653,668 Anderson Sept. 29, 1953 FOREIGN PATENTS132,433 Australia May 3, 1949

